The “Birthday Problem”

Defense attorneys interested in learning more about DNA statistics might find the following articles interesting because the “birthday problem” is analogous to looking for partial matches in a DNA database.  The birthday problem is a classic puzzle that asks  if you had a room full of people, how many people would you need in the room to make the odds of two people having the same birthday at least 50-50. Surprisingly, the answer is just 23.

In the “birthday problem,” when you do not designate a specific birthdate, you open up the opportunity for many pairs to be made from a much smaller sampling of people than if you specified a specific birthday.  The same applies in with DNA when searching a DNA database for any set of matching loci, rather than looking to match a specific set of loci to another distinct set of loci.

This NY Times post is part a 6-part series entitled “Me, Myself and Math” and does a great job of explaining the birthday problem. For folks wanting more in-depth information about how the birthday problem is useful for understanding trawling of DNA databases for partial matches, take a look at this article by David H. Kaye.


1 Comment

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One response to “The “Birthday Problem”

  1. By Any Chance, do you have even more posts just like this particular
    1 termed, The Birthday Problem | Forensic Science in North
    Carolina? I just want to read even much more regarding it.
    Many thanks.

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